Apparatus and method for handling pulverized fuel



May 12, 1931. ca. A...CONRATH 1,804,593

APPARATUS AND METHOD' FOR HANDLING PULVERIZE ID FUEL Filed May 10, 1926I s Shgets-Sheet 1 May 12, 1931. G. A. CONRATH APPARATUS AND METHOD FORHANDLING PULVERIZED FUEL Filed May 10, 1926 3 Sheets-Sheet 2 M m w m vsMay 12, 1931. G. A. CONRATH 1,804,593

APPARATUS AND METHOD FOR HANDIDING PULVERIZED FUEL 3 Sheets-Sheet 5Filed May 10, 1926 Patented May 12, 1931 UNITED STATES PATENT OFFICEGEORGE A. CONRATH, OF DES MOINES, IOWA, ASSIGNOR F ONE-HALF To CHARLESSt DENMAN, OF DES MOINES, IOWA APPARATUS AND METHOD FOR HANDLINGPULVER-IZED FUEL Application filed May 10,

5 in that form, it is possible to secure much higher thermal efiiciencyon account of the more complete combustion. The usevof pul-' verizedfuel permits great flexibility and reduces the standby and low bankinglosses.

One of the great problems in handling pulverized fuel arises from the,cost of operation. 7

and maintenance. It is my purpose more particularly therefore to providean apparatus and method whereby coal maybe fed to a pulverizer by asuitable feeder, together with a supply-of air,

which is preferably preheated. The coal is pulverized and when takenfrom the pulverizer'is separated or divided into the fine coal dust,which is conductedto the burner by air currents, and into thelargerparticles, which are carried by air back to the pulverizer ormuller. v 1

It is my purpose to provide in such a mechanism a simple, eflicient anddurable structure, which can be manufactured and maintainedeconomically.

In order to reduce the labor cost in handling coal and maintainefliciency in carrying out the entire process, it is desirable-that thevarious operations should he automatically controlled according toconditions in the furnace or the boiler.

It is therefore a further purpose of my present invention to providemeans and a methodforautomatically controlling accord. ing to boilerpressure, for instance, the feed-.

ing mechanism, the air supply to the.coal

passing through the machine, the pulverizer, the coal separator means,and the supply of powdered coal to the combustion chamber.

1926. Serial in. 107,966.

iliary supply of air tothe furnace through the draft door. incooperation and synchronism with the other automatic controls mention edabove. I further connect the control mechanism with a damper located forinstance in the stack. I thus eliminate as far as may be the necessityfor constant supervision and reduce the labor cost incident to thepractice of the process in the use of the apparatus.

It is my object in connection with such a mechanism to provide novelfeatures of mech.' anism for accomplishing the various purposes thusoutlined.

' The feeder structure is shown in my copending application filedJanuary 16, 1926, Serial No. 81,628.

With these and other objects in view, my invention'consists in the stepsof the process hereinafter explained and in the construction,arrangement and combination of the various parts of my'apparatus,whereby the objects contemplated are attained, as hereinafter more fullyset forth, pointed out in my claims, and illustrated in the accompanyingdrawings, in which:

1 Figure 1 is an elevation of an apparatus embodying my invention withwhich my method may be used. n

Figure 2 isa side elevation of the same apparatus, whereby my method maybe practiced, some parts being shown in section and other parts beingbroken away.

Figure 3 is a plan view of the feeder, with parts omitted and partsshown in section taken on theline3-3 of Figure 2. A,

Figure 4 is a sectional view of'the feeder taken on the line 44.pfFigure 3; and

Figure 5 is a detail, sectionalview taken on the line 5-5 of Figure 2.

p In'the accompaning drawings, whereby I have illustrated an apparatusembodying my other source of supply and discharges it into thepulverizer or muller.

Referring to Figures 3 and 4, it may be noticed that the feeder 10comprises a suitable casing 10a, in which is journaled a shaft 12,.whichprojects through one end wall of the feeder.

Fixed on the shaft 12 just below the fuel in-' take pipe 11 ,is a a feedwheel 13, which is formed with the radially projecting blades 14,between which are formed the fuel conducting pockets 15.

Just above the feed wheel 13 is a deflector plate 16 for directing thefuel into the pockets and preventing it from dropping into the airintake inlet hereinafter referred to.

The feeder casing 10a has at one side the air inlet portion 17 to whichthe heated air is supplied through a suitable pipe 18.

For controlling the supply of air to the feeder, I provide the throttlevalve 19, having the stem 20 projecting to a point outside the airpassage and having on its outer end the is transmitted to the shaft 12through the gears 23 and 22.

It may be mentioned in this connection that ,a suitable clutch maybe--provided for this P po I provide in connection with the feed wheel'-means for controlling the amount of fuel fed by the wheel to thepulverizer.

Mounted in the casing 10 and slidably arranged on the shaft 12 is asliding sleeve drum member 26, having one end by the shaft 12, as at 27,and having the other end slotted as at 28, to snugly fit and "slidealong the blades, 14. This sliding sleeve drum 26 is arranged to be slidlongitudinally on the shaft 12 in such manner as to regulate theoperating size of the pockets 15 by reducing or increasing theireffective length.

The shaft 12 or a portion of its length is hollow and slidably receivesan actuati rod 29, which is connected with the sliding s eeve drum 26within the casing 10 by means of a pin 30, extending through a slot 31in the wall ofthe' hollow portion of the shaft 12.

' The mechanism for controlling the rod 29 for thus adjusting the feederwill be hereafter referred to.

Pulvenlzer' 1 Fuel is. discharged from-the pockets 15 through a passage32 at the lower part of the -49 and 50 and the belt 5 carried directlyiiange 39 terminating in a downwardly openmg, raised, annular channel40.

This whole device forms what may be called a supporting disc B fortheshaft 37 and the pulverizer or muller pan A.

Arranged in a circle around the bottom of the casing 33 within thecompartment 35 are rollers or wheels 41.

Near the periphery of the disc B on its under side is an annular grooveor the like 41, which receives the u per edge of the wall 34 to make ajoint sufficiently tight to retain lubricant within the chamber 35 andyet to permit free rotation of the shaft 37 and disc B.

On the disc B on the under side thereof is-mounted a ring 42, having atits periphery an upwardlyiextdnding, annular flange 43, provided with;teeth 44.

The device justdescribed forms a worm wheel, which I have indicatedgenerally by the reference character C.

A shaft 45 extends through the wall of the casing 33 and through thewall 34 and has on its inner end a worm 46, shown in Figure 5 in meshwith the teeth 44 of the worm wheel C. The shaft 45 is actuated from'amotor 47 having the shaft 48. by means of pulleys Resting upon lugs 52on the frame members 3341 is the bottom member 53 of the pulverizercasing 33. The bottom member has an annular, upwardly extendingperipheral side wall 54.

The diameter of the casing 33 at its upper part is a little less thanits diameter at its lower part, as shown.

The shaft 37'extends upwardly through the bottom 53 of the casing 33,and a suitable. stuiiing box structure 55 affords a joint, which willprevent the escape of coal dust.

The grinding pan, A has inset into its upper surface an annular,sectional wear plate 56, the details of which are not here described.The grinding or pulverizing pan A has a series of radially projectingarms 57,

-' which support, an annular, sectional slotted ring 58 through whichtheground fuel may drop downwardly upon the bottom 53. e

Certain of thearms 57 support downwardly, projectin scraper blades 59,the lower edges of whic are adjacent to the bottom 53 for scraping theground fuel to the discharge opening in the bottom.

Mounted on the shaft 37 just above the bottom 53 is a radiallyprojecting scraper arm 60, which has the same purpose.

The arms 57 also carry an upwardly extending peripheral rim or wall 61,which really forms partb of the pulverizing pan A.

Within the casing 33 are spaced muller wheels 62, having shafts 63,projecting through the side walls of the casing 33. The side walls areprovided with suitable slots 64 to permit limited up and down swingingmovement of the shaft63 and the muller Wheels. The outer ends of theshafts 63 are journaled in bearings 64a carried b the wheel carriers oryokes 65, which are suitably pivoted to the upstanding arms 66 on theframe member 33a.

The muller wheels 62 thus rotate freely and are permitted slight up anddown movement.

The shafts63 carry fiber plates 67 adjacent to the slots 64 for coveringthe slots and preventing the escape of fuel therethrough.

Powder fuel handling mechanism A fuel pipe 68 extends from the bottom ofthe casing 33 near the center ofthe bottom member 53 laterally, as shownin Figure 2, for conducting the pulverized fuel away from the pulverizercasing.

The pipe 68 leads to a fan casin 69, in which is a fan or the like ofany sui'ta le construction, not shown, operated from the motor 70. Thefan casing 69 discharges'into a conducting pipe 71 leading to the top bfthe pulverizing casin 33.

The powdered ml, which travels through I the pipe 68 is separated intothe finedust,

which is conducted to the combustion chamber, and the larger particles,which are driven by the fan structure 69 and the air current through thepipe 71 back tothe pulverizer chamber.

The manner of accomplishing this separation will now be described.

A pipe 72 communicates with the top of thepipe 68 and leads .to a fanstructure 73, in which is a fan of any suitable construction, not shownhere in detail, operated from a motor 74.

A the combustion chamber.

From the fan structure 73, the fine dust is Automatic regulatingstructure The motor 25 may rest upon a suitably supported shelf or thelike 78. A bell crank lever 79 is pivotally mounted, as for instance at80, on the shelf 7 8. One arm of the bell crank lever 79 is connected asat 81 with the control rod 29 hereinbefore referred to, in such mannerthat the rocking of the bell crank lever will move'the rod 29longitudinally, but

'will permit the free rotation of the rod. Thus by rocking the bellcrank lever 79, the feed wheel maybe controlled for regulating theamount of coal delivered tothe pulverizer.

It is desirable that the various operations of the machine should besimultaneously automatically controlled for controlling the rocking ofthe bell crank lever according to the condition of the furnace andboiler.

I provide a diaphragm casing 82 'having therein a flexible diaphragm 83,subject on one side to steam pressure from the boiler through the pipe84. On the other side of the casing 82 is a tubular extension 85.

The diaphragm 83 has ahead 86 to which is connected a rod 87 extendedthrough the casing 82.

In the end of the extension 85 is an adjustable sleeve 88, having athreaded connection with the extension 85. A coil spring 89 is mountedon the rod 87 within the extension 85 and casing 82 and bears againstthe head 86 and the adjustable sleeve 88.

By adjusting the sleeve 88, the tension of longitudinally and rockingthe bell crank. lever 79 for adjusting the sleeve drum 26 for regulatingthe size of the pockets 15, and consequently the amount of coal fed tothe pulverizer. r p

When the steam pressure goes down, the

' operation of the parts is reversed by virtue of the action of thespring 89. v

- A rod 91 is pivoted to the other arm of the ,bell crank lever 79, asat 92 (Figure 2). At

the lower end of the rod 91 is a yoke 93, the

arms of which extend downwardly on opposite sides of the pipe 72.

The arms of the yoke 93 are connected by pins .94 extending throughslots 95 in the pipe 72 with the sleeve 76, so that by raising orlowering the-rod 91, the sleeve 76 may be raised or lowered. v

It thus follows that when the bell crank lever 79 is actuated accordingto steam pressure, the sleeve 76 is slid up or down as the case may be.When the steam pressure goesup, the sleeve 76 is raised, and less fuelwill be drawn fromthe pipe 68 and delivered to the combustion chamber.On the other hand, when the steam goes down, the sleeve 76 will belowered into the passing stream of fuel and air, with the result thatmore fuel will be drawn to the combustion chamber.

In the pipe 72 is a butterfly control valve 96, the stem 97 of'whichprojects from the pipe and carries an arm 98. The arm 98 is connected bya link 99 with the rod 91, so that when the bell crank lever is actuatedby in creasing steam pressure for decreasing the feeding of coal andraising the sleeve 76, the valve 96 will be moved accordingly'towardclosing position; i

Provision is also made for simultaneously controlling the valve 19in thepipe 18 which conducts air to the feeder and therethrough to thepulverizer.

Referring to Figures 2 and 3, it will be seen that a bell crank lever100 is pivotally mounted as at 101. One arm of-the bell crank lever 100is pivoted to the rod 87. The other arm of thebell crank lever 100 isconnected by a link 102 with the arm 21 on the stem 20 of the valve 19in such manner that the movement of the rod 87, when it is actuated bythediaphragm on account of increasing the steam pressure, serves to rockthe stem 20 for moving; the valve 19 toward-closing position. 7

Similarly when the steam goes down, and the spring 89 moves the rod 87,as shown in Figure 2, toward the right, such movement .of the rod 87serves-to move the valve 19 to ward open position.

It isnot desirable, as has been said, to supply to the coal during itspassage through my apparatus all of the air which is necessary forproper combustion. When enough air is supplied for that purpose, thereis more danger of explosions due to the various causes, vsuch forlnstance as sparks that might be created in the machine.

' It is therefore desirable to have an auxiliary supply of air for thefurnace, and it is,

of course,desirable that this auxiliary supply be controlledautomatically in connection with the other controls herein mentioned. Aflexible cable 103 is connected with the upper end of the rod 91 andextends over a suitably mounted pulley 104 andanother pul- 55, ley 105to a furnace draft door 106. The arsteam pressure goes up for actuatingthe automatic controls, the draft door wlll be closed ormoved towardclosing position, and

when the pressure goes down, the draft door 69 will be opened.

.I also provide means for controlling a damper door 107, by-which air isadmitted to the stack 108. A flexible cable or the like 109 is connectedwith the door 107 and extends around the pulley 110, and is thenconrangement of the parts is such that when the nected with the cable103 in such .manner that when the door 106 is closed, the door 107 isopened, and vice versa when the door 106 is opened, the door 107 isclosed. 0

I will now explain in greater detail the practical operation of myapparatus and the method which I practice in feeding pulverized coal toa furnace either with my present ora similar apparatus.

p The coal is supplied to the pipe- 11 in an wheel. Theefiective size ofthe pockets will depend upon the position of the sleeve drum 26. If thatis at'the right-hand limit of its movement, as shown in Figure 3, thepockets will take and handle a large amount of fuel. If the sleeve drumis moved farther to the left, this will obviouslyreduce the size of thepockets and therefore reduce the capacity 95 of the feeder and'reducethe amount of coal discharged from the pockets 15 through the passage 32into the pulverizer.

It will, of course, be understood that the position of the sleeve drum26, which controls the supply of coal fed to the pulverizer will beregulated by the control mechanisms, 'hereinbefore described andhereinafter more particularly referred to, according to the oilerdemand.

Air is admitted to the feeder casing 10 through the inlet passage 17 andthe supply pipe 18. The air used is preferably preheatedin some suitableway, as for instance by taking it from the breeching or the hollow wallsof the furnace.

It will be understood, of course, that the air used is fresh air.

The use of-the heated air this manner serves two desirable purposes. Inthe first place, it helps to take moisture out of the fuel, and in thesecond place, all of the waste'hea't units thus used effect so much of asaving.

The supply of air'through the pipe 18 is ;controlled by meansof thevalve 19. This 12" valve 19 is actuated according to boiler demand incooperation and simultaneously with the control of the feeder.

The coal passes from the feed wheel 13 through the passage 32 into thepulverizer or muller. It is, of course, obvious, that the air suppliedtothe feeder casing passes into the pulverizer casing with the coal. Thepulverizer casing is substantially airtight.

The coal drops upon the grinding pan A' above the pan bottom, so thatvery finely should be increased. The increasing or and by the rotationof the pan comes directly into the path of the muller wheels 62. Scraperblades 113 are suitably supported on the pulverizer casing andincooperation with the pan serve to move the coal inwardly, so that itwill be in the paths of the muller wheels.

The pan is rotated from the motor 47, the shaft 48 of which transmitspower to the pulley 49, the belt 51, the pulley 50 and the worm shaft45. The worm 46 on the shaft 45 meshing with the teeth 44 rotates thesupporting disc B and the pul verizer pan shaft 37 and the pulverizerpan A.

The coal is ground'by the muller wheels 62 and the wear plate 56. Themuller wheels are permitted to rock up and down for a limited distanceon account of the pivoted mountings of the carriers-65 on the arms 66.

The fine coal dust drops downwardly through the screens 58. The scraperblades 113 stand perhaps one-sixteenth of an inch ground fuel may passunder them.

The finely ground fuel drops onto the bottom 53 and is shoved around bythe blades 59 and 60 and drops into the pipe 68, through which a currentof air is constantly passing during the operation of the fan devices 69'and 73.

As the current of ground COZIlJ fiI1d air passes through the pipe 68,the very fine fuel is drawn upwardly through the sleeve 76 and the pipe7 2 and passes through the fan structure 73 and thence through the pipe75 to the combustion chamber. The coarser coal passes out of thedischarge end of the pipe 68 and thence through the fan structure 69, bywhich it is blown through the pipe 71 back to the pulverizer. v

In order to insure the working of the machine with the maXimum ofefficiency and to reduce the cost of labor and superintendence to aminimum, I have provided the automatic control mechanisms hereinbeforedescribed.

It is obviously desirable that when there is an ample supply of steam inthe boiler, the furnace fire should be reduced, and that when the steamsupply goes down, the furnace {lire creasing of the fire is accomplishedby controlling the amount of coal fed to the pulverizer,and the amountof pulverized coal supplied to the combustion chamber.

The feeding mechanism is controlled from the diaphragm 83 in the mannerhereinbefore described.

The amount of coal supplied to the com the pipe 7 2 and theadjustment ofthe sleeve 76. The draft of air through the pipes just 4 .7

It will, of course, be understood that the mentioned is regulated by thevalve 96 in the ner hereinbefore described from the diaphragm 83. Thesleeve 76 issimilarly controlled from the diaphragm.

It has been found that it is highly desirable to control also the inletof air to the pulverizer, and this is accomplished by the mechanismhereinbeforc explained for controlling the valve 19.

It is obvious that it would be difficult to accurately control thesupply of fine coal to the furnace, if all thecoal groundshould beconducted to the furnace. It would, of course, not be desirable to havethe coal supply choke up, and I have therefore provided the means hereindescribed, comprising the fan structure 69 and the return pipe 71 forconducting back to the pulverizer, the coal not used for the furnace.

The step of my process, which involves carrying back to the pulverizer,some of the coal, is' also important because it is desirable to use forcombustion only the coal which has been ground the finest.

It will, of course, be understood that the coal, which has been groundthe finest is subject to the mostcomplete combustion. Some coarserparticles of coal will be discharged from the pulverizer, and thesecoarser particles are carriedback for another grinding.

I have already explained that it is desirable to supply auxiliary airtothe combustion chamber. It is of course obvious that it'is desirable tocontrol this auxiliary air supply in accordance with boiler demand, andthis is accomplished by means of the automatic control for the door 106,which has already been described.

It is well-known that in any furnace, it is desirableto control thestack door, and I have provided for the automatic control of that door107 as hereinbefore explained.

A general advantage arises from the flexibility which is possible in theuse of my apparatus and process.

,I will now call attention to some of the 6 features of my "apparatusand machine by tion takes place.

Attention is called to the arrangement of the parts wherein a pulverizeror muller of thiskind is contained within a substantially airtightcasing which I believe to be a novel feature of structure, and whichmakes possible the use of air in the manner herein explained.

particular form of, mechanism,which I have shown here, is intended to beillustrative,

and that I do not desire to limit myself to the specific form ofmechanism disclosed.

I claim:

5 1. In an apparatus of the'class described,

a pulverizer, fuel feeding mechanism for supplying fuel thereto, meansfor supplying air to the feeding mechanism to be mixed with the fuelbefore the fuel enters the pulverizer,

3 means-for Withdrawing fuel from the pulverizer, and means forsimultaneously controlling the feeding mechanism, the supply of air tothe feeding mechanism and the & drawing of fuel from the, pulverizer.

2. In an apparatus of the class described,

a pulverizer, fuel feeding mechanism for 3. In an apparatus of the classdescribed,

a pulverizer, means for feeding fuel thereto, means for withdrawing fuelfrom the pulverizer and separating the finer from the coarser fuel, andmeans for simultaneously, cooperatively controlling the feeding meansandthe fuelwithdrawal .and separating means whereby ademand for more uelcause coarser fuel to be drawn with the fine fuel in the separatingmeans. 4. In an apparatus of the class described, a pulveriz'er, fuelfeeding mechanism for supplying fuel thereto, means for supplying'air tothe feeding mechanism, means for drawing fuel from the pulverizer'andreturning it to the pulverizer, means for sepa'ratingthe finer portionsfrom the fuel being returned to thepulverizer, and means forcooperatively controlling the feeding mechanism, the supply of airto thefeeding mechanism, and thedrawing of the finer portions of the fuel fromthe Ifuel drawing and returning means.-

a v 1 5. In an apparatus of the class described, to a steam plant havinga combustion chamber, means for separating crushed fuel into finer andcoarser parts and conducting the finer fuel to thecom bustion chamber,comprising a conducting pipe, a means for creating air currentstherethrough, a second pipe leading from the upper part'of the firstpipe for taking-off the finer fuel and conducting it to the combustionchamber, a means for creating a draft of air through the second pipeaway from the first pipe, a sleeve'in the second p1 e, means foradjusting the sleeve v for inserting it to different distances ofprojection into the first pipe, a valve in the second. pipe, and meansfor cooperatively, controllingthe sleeve and valve.

conducting the finer parts to the combustion 6. In an apparatus of theelm described, a steam plant having a combustion chamber and a boiler, afuel crusher, means for separating crushed fuel into finer and coarserparts and returning the coarser parts to the m crusher, means forconducting the finer parts to the combustion chamber, comprising aconducting pipe, means for creating a draft of air therethrough, asecond pipe leading from the upper part of the first pipe for taking-offthe finer fuel and conducting it to the combustion chamber, means forcreating a draft of air through the second pipe away from the firstpipe, a sleeve in the second pipe, means for adjusting the sleeve forprojecting it different distances into the first pipe, a valve in thesecond pipe, a draft door for controlling auxiliary air su ply to thecombustion chamber, and means or cooperaitdively controlling thevalveand the draft oor; 7

7 .In an apparatus of the class described, a steam plant having acombustion chamber and a boiler, means for separating crushed fuel intofiner and coarser parts and con-. ducting the finer parts to thecombustion chamber, comprising a conducting pi a means for creating adraft of air t ere- ,through, a second pipe leading from the upper partof the first pipe fortalcing off the finer fuel and conducting it to thecombustion chamber, means for creating a draft of airthrough the secondpipe" away from the first pipe, a sleeve in the second pi e, meansforadjusting the sleeve. for projecting it different distances into thefirst pipe, a valve in the second pipe, a draft door iforcontrollingauxiliary airsupply to the combustion cham .ber, and means forcooperatively controlling the valve,-the draft door and the sleeve. 8.In an apparatus of the class described, a steam planthaving a combustionchamher and a boiler, means for separat' crushed fuel into finer andcoarser parts did chamber, comprising a conducting pipe, means forcreating a draft of air therethrough, a second pipe leading from theupper part of the first pipefor taking ofi the finer fuel. andconducting it to the combustion chamber, means for creating a draft ofair through-the second pipe, a sleeve in the second pipe, means foradjusting the sleeve for pro ecting it differentdistances into the firstpipe, a draft door for controlling aux- .iliary a1r supply to thecombustion chamber, a fuel pulverizer, a means for feeding fuel thereto,and means for coo ratively controlling the sleeve, the draft oor and thefeeda ing means. r r

9. In an ap aratus of the class described, a steam plant having acombustion chamber and a boiler, means for separating crushed fuel intofiner and coarser arts and conducting the finer parts to e combustionchamber, comprising a conducting pipe,

air through the. second pipe, a sleeve in the second pipe, means foradjusting the sleeve for projecting it different distances into thefirst pipe, a draft door for controlling auxiliary 'air supply to thecombustion chamber, and means for cooperatively controllingihe sleeveand the draft door according to the steam condition in theboiler.

10. In an apparatus of the class described, a steam plant having acombustion chamber and a boiler,'means'for separating crushed fuel intofiner and coarser parts and conducting the finer parts to the combustioncham' ber, said means comprising a horizontal conducting pipe, means forcreatinga draft of air therethrough, a vertical pipe leading from theupper part of the first pipe for taking off the finer'fuel andconducting it to the combustion chamber, means for creating a draft ofair through the second pipe, means for supplying auxiliary air to thecombustion chamber, a sleeve in said vertical pipe, means for adjustingthe. sleeve for projecting it different distances into the first pipe, adevice for controlling said supply of auxiliary air to the combustionchamber, a fuel pulverizer having discharge connection with saidconducting pipe, a means for feeding fuel thereto, and means forcooperatively controlling thesleeve, the device, and the feeding meansaccording to the steam condition in the boiler.

11. In an apparatus of the class described, a steam plant having acombustion chamber and a boiler, means for separating crushed fuel intofiner and coarser parts and conducts second pipe leadin from the upperpart of the first pipe for taiing off the finer fuel and conducting itto the combustion chamber, means for creating a draft of air through thesecond pipe awayfrom the first pipe, a sleeve in the second pipe, means'for adjusting the sleeve for projecting it different distances into thefirst pipe, a draft door for controllin'g auxiliary air supply to thecombustion chamber, a fuel pulverizer, a means for feeding fuel thereto,and means for cooperative-c ly controlling the feeding means, the valve,

sleeve and the draft door according to the condition of steam in theboiler.

12. In an apparatus of the class described, a'steam plant havifiga'combustion chamber and a boiler, means forseparating crushed fuel'intofiner and coarser parts and conducting the finer parts 'to thecombustion chamber, comprising a. conducting pipe,

means for creating a draft of air therethrough, a second pipe leadingfrom the upperpart of the first pipe for taking off the finer fuel andconducting it to the combustion chamber, means for creating a draft ofair through the second pipe, a sleeve in said second pipe, means foradjusting said sleeve for projectin it dilferent distances into thefirst pipe, a evice for controlling auxiliary. air supply to thecombustion chamber, a fuel pulverizer having discharge connection withsaid conducting pipe, a means for feeding fuel thereto, means forcooperatively controlling the feeding means, the sleeve and theauxiliary air control device, means for supplying air to the feeder, andmeans for simultaneously controlling such air supply in cooperation withsaid first controlling means.

13. In an apparatus of the class described, a steam plant having acombustion chamber and a boiler,.means for separating crushed fuel intofiner and coarser parts and conducting the finer parts to the combustionchamber, comprising a conducting pipe, means for creating a draft of airtherethrough, a second pipe leading from the upper part of the firstpipe for taking off the finer fuel and conducting it to the combustionchamber,

means for creating a draft of air through the second pipe away from thefirst pipe, a sleeve in the second pipe, means for adjusting the sleevefor projecting it different distances taneously controlling such'airsupply in cooperation with said first controlling means.

a steam plant having a combustion chamber and boiler, a pulverizer, fuelfeeding mechanism for supplying fuel thereto, means for supplying air tothe pulverizer, means for drawing'fuel from the pulverizer and supplyingit to the combustion chamber, and means for simultaneously controllingthe feeding mechanism,.the supply of air to the pulverizer, and thedrawing of fuel from the pulverizer, according to the pressure of- 14.In an apparatus of the class described, 1

controlling the feeding mechanism, air supplying means and separatingmeans.

16. A method of handlin coal comprising the supplying of air to t e coalbefore it is pulverized and during the pulverizing operation, theremoval of the'coal from the point of pulverizing and the simultaneouscooperative controlling of the supply of coal for pulverizing, thesupply of air to the coal, and the removal of the coal from the point ofpulverizing. C

17. In a process of pulverizing coal, feeding the raw coal to apulverizing zone and pulverizing the same, supplying air to the coalbefore it is pulverized and during the pulverization thereof, removingthe fuel from the pulverizing zone, and simultaneously and:cooperatively controlling the supply of air and fuel withdrawal.

18. The process of feeding coal for pulverizing, pulverizing the coal,supplying air to the coal before and while it is being pulverized,withdrawing the coal from the point of pulverizing, and separating itinto finer and coarser portions, and simultaneously, cooperativelycontrolling the supply of coal for pulverizing, the air supply to thecoal and the withdrawal and separation of the coal.

19. The process of preparing and feeding fuel to a steam plant having acombustion chamber and a boiler, comprising feeding the fuel to apulverization zone, pulverizing the fuel, supplying air to the fuelbefore and while it is being pulverized, withdrawing the fuel from thepoint of pulverization, conveying it-to the combustion chamber, andsimultaneously, cooperatively controlling the air su'p'ply,the operationof the fuel withdrawal and movement of the fuel to the combustibnchamber accord-ingtg the pressure of steam in the boiler.

ized fuelto 20. The process of preparing and feeding fuel to a steamplant having a combustion chamber and a boiler, comprising pulverizingthe fuel, supplying air to the fuel before and while it is beingpulverized, conveying the fuel to the combustion chamber, andsimultaneously, cooperatively controlling the air supply and theoperation of the fuel conveyance to the combustion chamber and thesupply of fuel for pulverizing. Y

21. The process of preparing and feeding fuel. to a steam plant having acombustion chamber and a boiler, comprislng pulverizing the fuel,supplying air to the fuel before and duringlthe pulverizing, conveyingthe pulverel to the combustion chamber, and simultaneously,cooperatively controllin air supply and the movement of the puTverizedfuel to' the combustion chamber, and also simultaneously, cooperativelyregulating, controlling and suppl' ing .an additional amount of air tothe coin ustion chamber.

22. The process of preparing and feeding a steam vplant having acombustion the chamber and a boiler, comprisin feeding the fuel to apulverization zone, pu verizing the fuel, supplying air to the fuel asit is fed and whlle in the pulverization zone, withdrawing the fuelfromthe pulverization zone and separating the finer from the coarserpulverized fuel and conveying it to the combustion chamber, the coarserfuel being returned to the zone of pulverization and further treatedtherein for pulverization, and simultaneously, cooperatively controllingthe air-supply, the supply of fuel to the combustion chamber, the supplyof fuel to the pulverization zone, and the separation operation, 23. Theprocess of preparing and feeding fuel to a steam plant. having acombustion chamber and a boiler, comprising pulverizin the fuel,supplying air to the fuel before an during the pu verizing, conveyingthe pulverized fuel from the point of pulverizing to the combustionchamber, and simultaneously, cooperatively controlling the air sup plyand the movement of'the pulverized fuel to the combustion chamber, andsimultaneously, cooperatively controlling, regulating and supplying anadditional amount'of air to the combustion chamber, the coarserparticles of fuel being separated from the finer particles and returnedfor further pulverizing asthe fuel is conveyed along toward thecombustion chamber.

In an apparatus of the-class described,

'a steam plant having a combustion chamber and a boiler, means forseparating crushed fuel into finer and coarser parts conducting thefiner parts to the combustionchamber,

comprising a conducting pipe, means for creating a draft of airtherethrough, a second pipe leading from the upper part of the firstpipe for taking off the finer fuel and conducting it to the combustionchamber, means for creating a draft of air through the second pipe, asleeve slidably mounted in said second pipe, means for adjusting saidsleeve for projecting it difierent distances into the first pipe, adevice for controlling auxiliary air supply to the combustion chamber,and means for cooperatively actuating the sleeve ad usting means and thedevice, a fuel pulverizer having discharge connections with'said con.-ductin pipe, ameans for feeding fuel thereto, an means forcooperativelycontrolhng the feeding means, and the sleeve, means for supplying air tothe feeder, and means forsimultaneously controlling such air supply incooperation with said first controllmg' means. 1

Des Moines, Iowa, April 16, 1926. V

GEORGE A. CONRATH.

